On Mon, Nov 29, 2010 at 6:36 PM, Amit Kucheria <amit.kuche...@linaro.org> wrote: > On Mon, Nov 29, 2010 at 3:58 AM, Michael Hope <michael.h...@linaro.org> > wrote: >> >> I sat down and measured the power consumption of the NEON unit on an >> OMAP3. Method and results are here: >> https://wiki.linaro.org/MichaelHope/Sandbox/NEONPower >> >> The board takes 2.37 W and the NEON unit adds an extra 120 mW. >> Assuming the core takes 1 W, then the code needs to run 12 % faster >> with NEON on to be a net power win. >> >> Note that the results are inaccurate but valid enough. >> > > Thanks for doing this Michael. Very interesting numbers. Some > questions/comments: > 1. What is the load on the system when running your loop?
It's the only process running, so the load average should be 1. > 2. 2.73W for the board certainly means no PM. So the actual cost of NEON > will be higher when you run a kernel with working PM. Yip, but the absolute cost should be the same. The interesting question is: given a workload that takes, say X CPU seconds at full power, how much faster does the NEON version have to be to use less total energy? > 3. What percentage of the packages in the main repo of Ubuntu generate NEON? Very few at the moment. Only the ones that have NEON specific backends really, but that includes X via pixman and any video or audio decoders. -- Michael _______________________________________________ linaro-dev mailing list linaro-dev@lists.linaro.org http://lists.linaro.org/mailman/listinfo/linaro-dev
